The number of rubella patients reported nationwide this year has jumped more than fivefold to 496 from 93 in the previous year, with many cases reported in and around Tokyo, a national institute warned Wednesday.
The patients included many men in their 30s to 50s who have not been sufficiently vaccinated against the highly contagious disease that is often transmitted through coughing and sneezing, according to the National Institute of Infectious Diseases.
In the week through Sept. 9, the number of current rubella patients rose to 127 from 81 in the previous week, according to the institute, which especially urged adult men to get vaccinations in order to protect women and children. By prefecture, Tokyo had the most patients with 32, followed by 27 in Chiba, 19 in Kanagawa, and 11 each in Saitama and Aichi, data showed.
Rubella can have a serious health impact on babies if contracted by women in the early stages of pregnancy as it tends to cause birth defects such as heart disorders, hearing impairments and cataracts.
Vaccination is effective in preventing infection but women who are already pregnant cannot be inoculated as the vaccine itself is feared to have an impact on the child. Notable rubella symptoms are fever, sore throat, and a rash. Its incubation period is two to three weeks.
Japan experienced a major rubella outbreak in 2013 with over 14,000 people contracting the disease. There has been a resurgence in the number of cases since late July, with the annual number of patients reaching the highest level since 2014.